A police helicopter buzzed overhead. A Tampa Fire Rescue engine and rescue vehicle set up out front. Students were held in their classrooms. A bomb-sniffing dog was brought out.

There were no gunshots — only fireworks ignited in a hallway.

But the response was a glimpse of the reaction authorities would bring to a school shooting here.

"Everybody's on edge right now," school district spokesman Stephen Hegarty said. "I think even if we weren't living post-Sandy Hook, people still would have responded like that, but it was comforting.

"To see that you get such a quick response, that gives you a lot more confidence if something does happen."

A student who police said lit the fireworks was arrested on charges that include inciting a riot.

Thursday's incident came more than a month after the Dec. 14 mass shooting at Sandy Hook Elementary School in Connecticut, which prompted a national discussion of gun laws and school security policies.

In the aftermath, Hillsborough superintendent MaryEllen Elia proposed a plan to put armed guards in all of the county's elementary schools, which the School Board later rejected. Similar plans have been discussed, but not implemented, by elected officials in Pinellas and Hernando counties.

What effectively became an impromptu school shooting drill for local authorities began about 2:20 p.m. when a caller to 911 reported gunshots inside the school at 5000 N Central Ave. near Seminole Heights.

According to a chronology released by Tampa police, the school resource officer started searching for the source of the noise, and by 2:24 p.m. was joined by dozens of police officers, who searched the school floor by floor.

Tampa Fire Rescue units arrived at 2:25 p.m. and set up a staging area.

At 2:26 p.m, officers found evidence fireworks had been set off in the southwest portion of the school. At 2:30 p.m., a bomb-sniffing dog searched the building for any additional explosives.

The official number of officers responding was 53, but Assistant Chief John Bennett said it was closer to 75, including those who didn't have time to check in before entering the school.

"This is something that put a lot of people in danger for something that we wouldn't consider a prank," Bennett said. "It was a crime."

Police arrested a 17-year-old student afterward and took her to the Hillsborough County Juvenile Assessment Center on charges of inciting a riot and tampering with evidence.

She was caught on school surveillance video setting off the fireworks, police said. A teacher identified her and when questioned, police said, she admitted the crime. State records do not show any past arrests of her.

The lockdown of the school ended about 4 p.m. — letting students out of school for the day about an hour later than usual.